Diary of a Network Geek

Guess who’s spending the weekend upgrading the company’s main server?

Finally after dealing with an aging server for too long, we’re upgrading.  And, not a minute too soon, either.  I have the joy of migrating Active Directory from a Windows 2003 server to a Windows 2012 server.  Not to mention, I get to migrate printing services, an iSCSI array connection, DNS and DHCP.  Wee!  What fun!

Well, I suppose that’s why I get the “big bucks”, right?  A system administrator’s work is never done!

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DNS has inherent weakness.

In it’s current form the Domain Name System, by it’s open nature, is pretty primed for exploitation.
Some of these attacks are more obvious than others, but there are two that I find particularly troubling.  More so that I can see them being used together to really mess with a website owner.
The first of these two attacks isn’t new.  But, the fact that it isn’t new and has been dealt with before doesn’t mean that it has suddenly stopped being effective.  The attack is called “DNS poisoning” and it works by corrupting the DNS cache on a server, which then forwards those poisoned DNS records as legitimate to other, unsuspecting servers.  The end result is that the attackers can redirect traffic from a legitimate website to their own site.  It’s hard to flat out stop right now, though, once discovered, it can be fixed with relatively little trouble.  This attack was used recently against several websites who were supporting SOPA and PIPA.  Of course, since these folks were trying to make a statement, it was pretty clear what had happened, so techs were working to fix it pretty quickly.
The second attack, which I would think include the first attack at its initial stages, is sub-domain hijacking.  In this attack, the attackers redirect the sub-domain of an existing site to another location.  This is a little more subtle and hard to detect.  In this case, the attackers are looking to profit from a well-established domain by “piggy-backing” on their reputation.  They poison the DNS records to point something like Viagra.google.com to their actual website, selling Viagra, or a site filled with spammy links that redirect a potential victim to their website selling Viagra, or whatever.   This attack takes a proactive system administrator to catch.  Since it doesn’t redirect any of the main, honest, actual site anywhere, but only uses its reputation to improve their own spammy links, it’s not always obvious that it’s going on.  Regular DNS record audits are about the only way to catch this, barring an angry end-user contacting the main site.

The internet is still a wild and wooly place sometimes, folks.  The reasons the professionals get paid what they do is because, theoretically, they have to deal with all that stuff and keep us safe!  Which reminds me, I have to go check my own company’s websites and DNS records, not to mention my own!
(The title, incidentally, was inspired by the movie that helped get me into this business, Sneakers. “Cattle mutilations are up.“)

No, not your personal name, network names!

Yeah, since I’ve been thinking about computer security a little in this new year and new decade, I’ve noticed a slightly disturbing trend.  Spammers have been working at redirecting you to compromised domains.  One way they do it is something called DNS cache poisoning.  Another is straight-up DNS hijacking.

Okay, let me back up a second.  For my slightly less-technical readers, DNS stands for Domain Name System.  That’s the system of servers that translates website names, like “www.google.com”, into addresses that your computer understands and can connect you to via a browser.  It’s how you found my blog, though you may not have even realized it.
DNS Hijacking is usually accomplished via a “rouge” server, which is a server setup by spammers to publish bad information.  The more usual method, I think, and more insidious, is DNS cache poisoning.  With that method, spammers trick good, valid DNS servers into updating their records with bad information.  Giving them poisonous information, if you will.

So, now, back to the hard-core server admins.  Last week I was reminding everyone that the start of a new year is a great time to change passwords, but it’s also a great time to check on other security issues, like your DNS.  Luckily, Michael Kassner over at TechRepublic has written a blog post titled Test your DNS servers for spoofability.  It’s worth a read and worth running through.  Maybe even making it a regular practice, to see if your DNS has been compromised.

Oh, and if you all want to read more about DNS, and how to implement it, there’s a great book from O’Reilly titled [amazon_link id=”0596100574″ target=”_blank” ]DNS and BIND[/amazon_link] that’s well worth owning.  Trust me.

Advice from your Uncle Jim:
"Our dignity is not in what we do but in who we are."